adsense auto responsive code with fixed height

i am heaving problem with adsense responsive ad unit i want a rectangle on both mobile and desktop and when i use responsive ad unit it get rectangle on desktop but on mobile it becomes a square (50%+ of the mobile screen)
i tried putting it in a div with fixed height but it’s not working and i found this solutions but changing style tag but it’s not working either

    <ins class="adsbygoogle"
<script async src="//"></script>
<script>(adsbygoogle = window.adsbygoogle || []).push({});</script>

i want a fix height so it’s rectangle on desktop and small rectangle on mobile